In an interview with The Washington Post published Sunday, Cook said Apple is "doing a lot of things" with augmented reality (AR), the technology that puts digital images on top of the real world.

Here's the full quote:

"I think AR is extremely interesting and sort of a core technology. So, yes, it's something we're doing a lot of things on behind that curtain we talked about."

The most popular example of AR today is the smash hit Pokémon Go, which lets you catch virtual monsters in the real world. But there are more extreme examples, like Microsoft's HoloLens headset and the startup Magic Leap's so-called cinematic reality that's being developed now. Magic Leap thinks AR headsets could one day replace many of the screens in your life by projecting whatever it is you need in front of your eyes.

Although this isn't the first time Cook has admitted Apple is interested in AR — he's spoken about it in broad terms before on recent earnings calls — this is the first time he's explicitly said the company is working on the technology. 

Apple has also snapped up several companies and experts in the AR space. And in January, the Financial Times reported that the company has a division of hundreds of people researching the technology.

However, it'll likely be several years before we see an AR or virtual-reality product from Apple, assuming we see it at all. It's still very early days for the technology, which has loads of limitations, like requiring users to wear dorky headsets or being tethered to a powerful computer.